Compound steam engine



Oct.'25,1938. v HLEN Z ET AL 2,134,466

COMPOUND STEAM ENGINE Filed Jan. 29, 1937 7 Sheets-Sheet 1 Oct. 25,1938;

H. LENTZ ET AL COMPOUND STEAM ENGINE 7 Sheets-Sheet 2 Filed Jan. 29,1937 Oct. 25, 1938. H. LENTZ ET AL COMPOUND STEAM ENGINE med Jan. 29,1937 7 Sheets-Sheet s m Z w\ fiflw W M w v 4 .6 4 kw &w m & \\H I, s Q Wa w m \R h v 5 a. pm .1 P w 5N .mwaa m /.AF w v W f r L. w Q

-0ct..25, 1933, V

H. LE NTZ Er AL COMPOUND STEAM ENGINE Filed'Janl 29, 1957 7 Sheets-Sheet4 Oct. 25; 1938. I H, LEQTZ ET AL 2,134,466

COMPOUND STEAM ENGINE Filed Jan. 29, 1937 7 Sheets-Sheet 5 I W w Oct.25, 1938. H LENTZ ET'AL 2,134,466

COMPOUND STEAM ENGINE Filed Jan. 29, 1937 7 Sheets-Sheet s oct'; 25,1938. H LENTZ ET A]. 2,134,466

- v COMPOUND STEAM ENGINE Filed Jan. 29, 1957 7 Sheets- Sheet 7 Patentedoer. 25, 1938] comomm STEAM ENGINE Hugo llentz, Berlin, Germany, andHugo Johannes Lents, Vienna, Austrla Application January 29,1931, SerialNo. 122,994 In Germany January 29, 1936 '1 Claims. (01. 121-102)Compound steam engines of the Woolf type with poppet valve gear areknown, in which these valves are arranged side by side at each end ofthe cylinder block and in which each of the valves is controlled by aseparate cam. However, the object of this arrangement, namely to keepthe steam passages short and the clearance small,

.is not entirelyattained.

It is likewise. known, in connection with single cylinder steam engines,toconstruct the two control valves with spindles located the one'withinthe other at each end of the cylinder, to thus arrangethem coaxially onebehind the other and control them by a common cam. .5 The invention goesstill farther, in that in compound steam engines of the Woolf type acombined cam controls the sets ohvalves arranged at each end of thecylinder block between high pressure and low pressure cylinders, eachset com- 'prising three coaxial valves arranged one behind the otherwith their spindles mounted one within the other. By this arrangement anextrelnely compact construction of the valves and consequently aconsiderable reduction in the clearing is obtained but at the same timethe whole gear drive is considerably simplified.

The combined cam serving for controlling the sets of valves can have allthree control surfaces for the admission, bypass and exhaust, in whichinstance it is driven by a cam shaft. It is then possible to use thecontrol surfaces for the exhaust also for-controlling the admission; ifthe admission valve is constructed as piston slide valve so that itopens later than the exhaust valve. The combined cam can,'however, bealso constructed as a two-part cam, one part having thecontrol surfacesfor the admission and the second part the control surfaces for bypassand .exhaust, each part being driven by a separate shaft. The combinedcam for controlling both sets of valves can be arranged in the middle ofthe cylinder, in which case the valve spindles mounted one within theother are directed the one against the other. The valve spindles may,however, also be outwardly directed, in which case a combined cam isarranged on each end of the valve chest. This arrangement presents theadvantage that in the case of repairs being necessary each set of valvescan be removed as a whole and replaced by a new set.

For closing the valves an elastic pressure medium .(for example steam)acting on the valve spindles is employed, which medium, however,

enables in the new arrangement the admission valves for the highpressure to open separately when starting so that the live steam isimmediate- 1y fed to the low pressure cylinder and there develops a highpulling moment until the normal running can begin.

Several embodiments of the invention are illustrated by way of examplein the accompanying drawings, in which:----

Fig. 1 is a longitudinal section on line 1-1 of Fig. 2 through the highpressure cylinder, the 1 low pressure cylinder and the valve chestinterposed between these two cylinders ofa compound steam engine of theWoolf type with control drive actuated in the middle.

Fig. 2 is an end view of the cylinder block on 15 larger scale.

t Fig. 3 shows on larger scale and in longitudinal section the valvechest situated at one end of the cylinder block with built-in valve set.

Fig. 4 shows the intermediate levers in side elevation.

Fig. 5 is a longitudinal section through the valve chest and valve setof a compound engine of the Woolf type, in which a cam shaft is providedat each end of the cylinder block for con- 25 trolling the valve set.

Fig. 6 is an elevation on a larger scale showing a combined cam actingon the valve spindles.

Fig. 'I is a section on line VII-VII of Fig. 6. Fig. 8 is a diagramshowing the curves of the 30 valve lifts in dependency upon the crankangle.

Figs. 9 to 12 show a cam drive, in which the Y admission cam is arrangedadjustable relatively to the exhaust cam and separately driven.

, Fig. 13 shows a section through the valve chest 35 of another form ofconstruction of gear employing single seat'valves.

Fig, 14 is a similar section with open by-pass valve.

Fig. 15' is a section showing a control valve for 40 the closing steamin the position corresponding to coasting of the engine.

Figs. 16 and 17 are diagrams showing, respectively, the position of thecontrol valve for starting the engine and for closing all valves.

The form of construction illustrated in Figs. 1 to 4 will first bedescribed. I

is a cylinder block of a compound engine with a high pressure cylinder 2and a' low pressure cylinder 3. At each end of the cylinder block 9 avalve chest 4 is cast between the two cylinders, the feed and exhaustpassages for the steam leading into this chest. In each valve chest anadmission valve 5, a by-pass valve 6 and an.exhaust valve 1-, arearranged coaxially one behind the jecting edge to of the valve chest 4.

other and effect the steam distribution for one, piston side of the twocylinders. For this purpose a cup-like member 8 is inserted in theendwali 8 of the valve chest and carries the lower seat of the exhaustvalve 1. The upper seat of the exhaust valve is arranged on an inwardlypro- Radial slots 9' in the tapered part of the cup member 0 guide theribs I of the exhaust valve 1 and preventthis .valve from turning. Theexhaust valve I shuts off a space H from the side of which an exhaustpassage I2 extends.

The seats for the by-pass valve I are arranged on a valve cage l3inserted in the valve chest 4. This cage can bear against the cup member9 and has an annular extension I4 which engages in a central bore in themember 9. The inner part of the valve cage i3 is of smaller diameterthan the outer part so that an annular space It remains between theby-pass valve i and the exhaust valve 1, said space being connected witha by-pass passage l6 leading to the low-pressure cylinder 3.

In the valve cage It a second valve cage i1 is arranged for theadmission valve I constructed as a piston slide valve. The valve cage I!has passages i8 which lead into an annular space I! situated above theby-pass valve I. A passage 20 leads from the annular space I! to one endof the high-pressure cylinder 2.

A space 22 situated above the admission valve 5 and closed by a cover IIis connected with the live steam'conduit by a laterally arranged tubularconnection 23 indicated in dotted lines in Fig. 2.

' As already mentioned, the spindles of the valves are mounted onewithin the other. For this purpose the spindle Ia of the exhaust valve Iis-a hollow spindle, which is mounted at one end in a central bore 9" ofthe valve cage 9 and at its other end in a central bore II in aninserted member It. The hollow spindle Ia accommodates the hollowspindle 8a of the by-pass valve 6 and in this hollow spindle 6a thespindle Ia of the admission valve 5 is mounted The ends of the spindlesproject into the cam shaft chamber 25 in which the cam shaft 24 and theother elements serving for controlling the valves are arranged. The camshaft 24 is oscillated in the gers 28b come into contactwith the end ofthe hollow spindle la.

On the other hand the by-pass valve 6 is actuated by a cam 28 which actson an interme diate lever 29 oscillatable about an axle 29.

x The free end of the intermediate lever 29 is also forked.- Its fingers29a engage between the fingers of the intermediate lever 28 andact onthe end of the spindle 6a of the by-pass valve- As in this constructionof the cam the lifting surfaces 2'! lift the admission-and exhaustvalves simultaneously, but the two valves must open'at difl'erent times,the high-pressure admissionvalve 4 must be constructed as piston slidevalve of springs.

with a certain overlapping, so that it opens later than the exhaustvalve 1. This presents the advantage that the acceleration of theadmission valve takes place already before it opens, so that theadmission passage is exposed very quickly and the steam can flow intothe high pressure cylinder without being throttled.

To maintain the gear elements permanently in contact and to return thevalves on to their seats, an elastic pressure medium such as steamacting on the valve spindles is employed instead For this purpose thefollowing arrangement is provided:-

Firstly, a bore 12 is provided in the cover ii, to which wet steam orsome other pressure medium is supplied through a conduit 3i. This mediumacts on a pressure piston 33 mounted in the bore 32, which piston ispressed against the spindle to of the admission valve into its closedposition. With a view to maintain also the other valves 5 and 6 inclosed position by steam pressure, the bottom of the valve cage II isconstructed as a hollow body 34, the internal space 35 of which isconnected by a bore 38 in one of the reinforcement ribs with a steamconduit 8|; The space 35 communicates by means of a bore 81 in thehollow spin e is with an annular space 85a produced by re using thespindle la of the admission valve from its normal diameter iii to asmaller diameter dz. The admission valve spindle 5a is pressed towardsthe right by the closing pressure acting on it. It can therefore beregarded as a rigid counter bearing-so that the pressure prevailing inthe chamber Ila presses the spindle 6a of the by-pass valve 4 towardsthe right with a pressure which acts in the annular chamber formedbetween the diameters iii-dz. The steam pressure prevailing in the space35 may also act on the end of spindle la of the exhaust valve. Thus, allthe valves are maintained under closing pressure during the service.

The steam conduits 30 and 3| leading respectively to the chambers 32 and35 are at the same time connected with a control valve 41 in a casing46, the valve being adjustable from the driver's stand through asuitable rod, not shown, and a lever e and serving at the same time asstarting and coasting pressure compensation device The valve 41 has apassage I and controls four passages in the casing 46. Passage a isconnected to the boiler of the engine, or to a compressed-air reservoir,by a pipe 53; the passages b and c are connected, respectively, to thecon duits III and'tl; and a vent passage d is connected to a dischargepipe d opening into the atmosphere. In the coasting position, Fig. 15,the supply of medium under pressure through conduit 83 and passage a isclosed by the valve 41, and the pipes 30 and 3| are connected toatmosphere. The valves brought into their open position by the cams thenremain in this position, so that free communication is establishedbetween the two ends of the cylinder.

When starting a compound locomotive, it is found necessary to firstsupply steam only to the large surface of the low pressure piston, so asto obtain a stronger pulling moment, whereas the high pressure cylinderis only connected up later.

space "a. The vent passage d is closed. The

pressure prevailing in the annular chamber Ila acts on the spindle inand brings the admission valve 5, as there is no counter-pressure, firstinto its open position. It then places the spindles 6a and 1a underpressure, so that the by-pass valve 6 and the exhaust valve 1 can,operate normally. If the regulator is then slowly opened, the live'steam passes from the chamber 22 through the opened admission valve .5and the by-pass valve controlled by the cam, directly into the low-pres-.sure cylinder 3 which, owing to the larger piston surface, can producethe power necessary for K starting. When it is desired .to change overto normal service, the control valve 41 is placed into the positionillustrated in Fig. 17 in which passages b and c, and pipes and SI, arecon nected to the supply passage 41, and the venturesage d is closed.All valves are now'under closing pressure. v f

Undercertain circumstances, if the pressure surfaces are correspondinglyproportioned, the pressure piston 33 can be entirely omitted in that, bygradually opening the regulator the increas-s ing steam pressure acts onthe spindle 5a of the admission valve until it is able to overcome thecounterpressure in the annular chamber a acting on the same spindle.when this occurs the admission valve is automatically brought into thecontrolling position and the engine then operates in its normal manner.

The form of gear shown. in Fig. 5 diflers substantially from that abovedescribed only in that the valve sets arranged on both ends of thecylinder block I are insertable as anaggregate into the bores of thevalve chest 4 and the valves are controlled each by a shaft arranged ateach end of the cylinders. In this instance each valve set comprises aninsert member 38 adapted tobe' slipped into the bore in the valve chest,in the end wall of which provided with a hub W a cup $9 is inserted,which carries the lower seat for the exhaust valve 1. The other seat ofthe exhaust valve is arranged on an annular extension 38" of the insertmember 38.

A valve cage 40 for the by-pass valve t is fitted in the casing '38 fromthe rear side thereof and bears at one end against the inner edge of theinsert member 38 and at its other end against the edge of the cup 39,this cage having an annularextension 40 which engages in the cup 39.

The valve cage 40, which carries the seats for the by-pass valve 6 haspassages 4! which establish communication between the space I! above theby-pass valve 6 and'the annular space i5; between the by-pass valve 8and the exhaust valve 1. A by-pass passage l6 branches from the space l5and leads to the end- 0f the low pressure cylinder 3. I I

A second valve cage 43 for the piston slide valve 5 is fitted in thevalve cage 40. This valve cage 43 bears at its inner end against thebottom of the valve cage 40 constructed as a'hollow body 35 and at itsouter side has an edge 43'. bearing against the edge of the valve cage40. The adder branches. The spindles 5a, to, la of the three valves aremounted one within the other and are "(is held in closed position bysteam pressure in the same manner as in the form of construction firstdescribed, and they are controlled in the same mannerby a cam shaft 24which is, however, here journalled in a hollow cover 45 covering thebore of the valve chest 4 and at the same time securing the differentinsertedmembers in the valve chest.

This construction of gear presents the advantage that in the event ofrepairs, the whole valve set can be taken out, after the removal of thecover 45, and a fresh valve set inserted. The dismantling and fitting ofthe gear can there- .fore be carried out in a very short time.

The operation of the gear is the same in both forms of construction. Iffor example, the cam '21 moves out of its middle position towards theleft, the exhaust valve 1 will first be opened and allows the exhauststeam to pass out of the low pressure cylinder 8 through the passage i6into the exhaust space H, from which it escapes through the tubularconnection l2. Shortly thereafter the same cam opens the admission valve5, so that live steam can pass from the space 22 through the inflowpassage 20 to the high-pressure cylinder 2 in which it expands after theclosing of the admission valve 5. During this time the by-p ass valveremains closed. Before the change of stroke and when the admissionandexhaust valves are closed, the by-pass opens. so that partly expandedsteam can pass from the high-pressure cylinder 2 through the passages toand it into-the low-pressure cylinder. in which, after the closure ofthe by-pass valve, the steam expands to its final pressure. At the otherend oi the cylinder the same series of operations take place onlydisplaced through a phase of'i80".

If the admissionvalve is not constructed as a piston slidevalve' but,like the other valves, as

an ordinary double seated poppet valve, separate lifting surfaces arenecessary for controlling the admission and inlet valves. In Figs. 6 and7 sucha gear drive is shown in section and elevation. The finger-shapedend of an intermediate lever 50, mounted on the axle 2t and actuated bya cam ti, bears against the end ofthe admission valve spindle ta. Toenable this intermediate lever W to swing out, the end of the spindle taof the by-pass valve t has an aperture 6b, through which the end of theintermediate lever til can pass. The forked end of an intermediate lever60 mounted on the axle 29' and actuated by a cam ti bears against theend of the spindle to of the by-pass valve 6. The spindle lq. of theexhaust valve I, however, is controlled by two intermediate levers Illmounted on the axle 2B and by two similarly shaped exhaust cams ii. Thetwo intermediate levers l0 bear against the endof the spindle la abovethe middle plane of the spindle. The lower half of the spindle has anaperture lb which allows the intermediate lever 60 to move withouthindrance.

The cams 5i, ti and II are in this instance cut from a block keyed onthe cam shaft 2 5. Where necessary, apertures areprovided in this blockto enable the unimpeded adjustment of the intermediate levers. Thecontrol surface of the admission cam 5i lags slightly behind the controlsurface of the exhaust cam H, so that *the exhaust valve opens earlierthan the admission valve as shown diagrammatically in Fig. 8

which only one shaft is arranged in the middle of the cylinder and twoshafts are provided at the cylinder ends.

In the gear above described the admission cam 5| is stationaryrelatively to the exhaust cam H. In Figs. 9 to 12 a gear drive is shownwhich differs from that previously described only in that the admissioncam 5| is adjustable relatively to the exhaust cam 6| for the purpose ofvarying the charge. For this purpose the shaft 24 is constructed as ahollow shaft, the cam block removed from between the exhaust cams H, andin this recess thus formed the admission cam is turnably arranged, thisadmission cam being driven by a second shaft 24a mounted in the hollowshaft 24 and extending through a central bore therein and coupledtherewith by projections engaging in longitudinal grooves in the shaft24a.

Each of these shafts is separately driven. Consequently the admissioncam can be displaced from the outside relatively to the exhaust cam, sothat it opens sooner or later, which enables the steam distribution tobe regulated within wide limits.

The kinds of gear above described employ double seated valves. The-samegear drive can also be employed forsingle seated valves which are easierto produce and by which primarily the clearance can be kept very small.They are suitable for more slowly running marine steam engines. Figs. 13and 14 show such a gear, wherein the valves are driven by a controldrive according to Figs. 6 and 7. Therefore, the corresponding gearelements are designated by the same references. Consequently, it is notnecessary to particularly describe this gear drive. Differing from thetypes of valve gear already described,'the valves are constructed asconeshaped single-seat valves 52, 62 and 12.; The by-pass valve 62 andthe low-pressure exhaust valve 12 are provided with flanges and 13,respectively, mounted to slide in bores 64 and 14, respectively, of thevalve casings I3 and 4, respectively. The stroke of the valves is equalto the width of the corresponding by-pass passages l6 and 20. Fig. 14shows the full-open position of the by-pass valve 52 in which the flange63 of the valve enters the bore 64 and the steam flows through theby-pass passage is from the high-pressure cylinder to the low-pressurecylinder without being throttled. The lowpressure exhaust valve 12 inits full-open position enters the bore 14 with its flange 13 so that theexhaust steam flows in the passage 20 without being throttled.

f the nested valve spindles a, 8a and la the latter is guided on aninsert member 48. The

spindles 6a and 1a are secured against turning. by a key 49 whichengages in longitudinal grooves in these spindles.

To maintain the valves in closed position it is suflicient in thisinstance to connect the internal space 55 of the gear housing with anevacuated space (for example to a condenser) by means of a conduit 58.

We claim:--

1. A compound steam engine of the Woolf type with valve gear, comprisingin combination a cylinder block having a high. pressure cylinder and alow pressure cylinder, sets of valves arranged at each end of saidblock, each set comprising an admission valve, a by-pass valve and anexhaust valve said valves arranged coaxially I that the block can beemployed for gears in one behind the other, valve spindles one carryingeach of said valves and mounted one within the other, and a combined camadapted to control said sets of valves.

2. A compound steam engine as specified in claim 1, in which thecombined cam is composed of two relatively adjustable parts, one parthaving a control surface for the admission, and the other the controlsurfaces for the by-pass and exhaust valves, and the two parts are eachdriven by a cam shaft.

3. A compound steam engine as specified in claim 1, in which thecombined cam is driven by a cam shaft and a control surface adaptedtocontrol both the exhaust valve and the admission valve for thehigh-pressure cylinder and said admission valve is constructed as pistonslide valve adapted to open later than said exhaust valve.

4. In a compound steam engine as specified in claim 1, in each valve seta valve cage carrying the by-pass valve, a valve cage carrying theadmission valve and mounted in said by-pass valve cage, a bottom on saidby-pass valve'cage constructed as a hollow body, and means for supplyingsteam to said hollow body to exert closing pressure on the spindles ofsaid by-pass and exhaust valves.

5. In a compound steam engine as specified in claim 1, in each valve seta valve cage carrying the by-pass valve, a valve cage carrying theadmission valve and mounted in said by-pass valve cage, a bottom on saidby-pass valve cage constructed as a hollow body, and means for supplyingsteam to said hollow body to exert closing pressure on the spindles ofsaid by-pass and admission valves, the spindle of the admission valvemounted in the tubular spindle of the by-pass valve being reduced to asmaller diameter and forming with the tubular spindle of the by-passvalve a chamber communicating with the space in said hollow body througha bore in the tubular spindle.

I 6. In a compound steam engine as specified in claim 1, in each valveset a valve cage carrying the by-pass valve, a valve cage carrying theadmission valve and mounted in said by-pass valve cage, a bottom on saidby-pass valve cage constructed as a hollow body, and means for supplyingsteam to said hollow body to exert closing pressure on the spindles ofsaid by-pass and admission valves, thespindle of the admission valvemounted in the tubular spindle of the bypass valve belng reduced to asmaller diameter and forming with the tubular spindle of the bypassvalve a chamber communicating with the space in said hollow body througha bore in the tubular spindle, a pressure piston subjected to theinfluence of a pressure medium and adapted to act on said admissionvalve spindle, and a cover plate having a bore coaxial with saidspindles and accommodating said piston.

7. A compound steam engine of the Woolf type with valve gear, comprisingin combination a cylinder block having a high pressure cylinder and alow pressure cylinder, sets of valves arranged at each end of saidblock, each set comprising an admission valve, a by-pass valve and andexhaust valve, said valves arranged co-axially one behind the other,valve spindles one carrying each of said valves and mounted one withinthe other, a combined cam adapted to control said sets of valves, ahollow seat for the by-pass valve. 9. cover plate having a bore, apiston on the outer end of the admission-valve spindle mounted to IIslide in the bore, a. reduced portion on the admission-valve spindledefining an annular chamber between this spindle and the tubular spindleof the by-pass valve which chamber communicates with the interior of thehollow seat through the tubular spindle, a casing; conduits connectin;the casing to a suppiyoi' fluid under pressure,

HUGO LENTZ. HUGO JOHANNES LENTZ.

